Executive brief
Budibase is a low-code platform for building and deploying internal tools and workflows. An unauthenticated attacker can bypass authentication on protected API endpoints by appending a public endpoint path as a query parameter, gaining access to sensitive user data including full user directory listings, account holder information, and the ability to trigger system actions. This exposure affects any public Budibase instance accessible over the internet.
Technical details
The vulnerability is a regex-based authentication bypass in the endpoint matcher middleware. The authenticated middleware compiles public endpoint patterns into unanchored regular expressions (no ^ or $ anchors) and tests them against the full request URL including query string. An attacker can append a public endpoint path as a query parameter (e.g., /api/global/users/search?x=/api/system/status) causing the regex to match in the query string portion, falsely marking the request as public and skipping authentication. The vulnerability affects only endpoints that lack secondary per-route authentication middleware; endpoints on builderOrAdminRoutes and adminRoutes are protected by independent middleware checks. Fixed in version 3.35.4 by anchoring regex patterns and/or using ctx.request.path instead of ctx.request.url.
Affected products
- Budibase Budibase all versions before 3.35.4
Timeline
- 2026-04-16: disclosed
- 2026-04-16: patched: version 3.35.4 released